Objective To observe the effect of muscone in regulating fatty acid synthase (Fas)/fatty acid synthase ligand (FasL) signaling pathway on cardiomyocyte apoptosis in rats with diabetic cardiomyopathy (DCM), and explore the mechanism of Chen Shuquan's theory of "warming and clearing collaterals" in treating DCM.

Methods SD rats were divided into blank group, DCM group, low-dose muscone group (0.68 mg/kg muscone), high-dose muscone group (2.72 mg/kg muscone), metformin group (140 mg/kg metformin), and high-dose muscone+recombinant human FasL protein (rh-FasL) group (2.72 mg/kg muscone+0.017 mg/kg rh-FasL), with 12 rats in each group. Except for the blank group, rats in all other groups were fed with high-fat feed combined with intraperitoneal injection of streptozotocin to construct a DCM rat model. After successful modeling, the rats were administered once a day for 6 weeks. After the last treatment, the changes in fasting blood glucose, left ventricular ejection fraction (LVEF), and left ventricular short axis shortening rate (LVFS) in rats were detected; Hematoxylin-eosin (HE) staining and Masson staining were applied to detect pathological damage and fibrosis degree of myocardial tissue, respectively. Spectrophotometry was applied to detect the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in myocardial tissue; TUNEL staining was applied to observe myocardial cell apoptosis; and Western blot was applied to detect the expression of cleaved aspartate specific cysteine protease-3 (cleaved-caspase-3), Bcl-2 associated X protein (Bax), Fas, and FasL proteins in myocardial tissue.

Results Compared with the blank group, the pathological damage to the myocardial tissue of rats in the DCM group was severe, the fasting blood glucose, MDA content, myocardial collagen area fraction and apoptosis rate of myocardial cell, and expression of cleaved-caspase-3, Bax, Fas, and FasL proteins increased, while the LVEF, LVFS, and activity of SOD decreased (P < 0.05); compared with DCM group, pathological damage of myocardial tissue was reduced in the low-dose muscone group, the high-dose muscone group and the metformin group, and fasting blood glucose, MDA content, myocardial collagen area fraction, myocardial apoptosis rate and cleaved-caspase-3, Bax, Fas and FasL protein expression were decreased, and the activities of LVEF, LVFS and SOD were increased (P < 0.05). Compared with low-dose muscone group, pathological damage of myocardial tissue was relieved in the high-dose muscone group and the metformin group, fasting blood glucose, MDA content, myocardial collagen area fraction, myocardial apoptosis rate, cleaved-caspase-3, Bax, Fas and FasL protein expression were decreased, and LVEF, LVFS and SOD activities were increased (P < 0.05). Compared with the high-dose muscone group, the pathological damage to the myocardial tissue of rats in the high-dose muscone+rh-FasL group was intensified, the fasting blood glucose, MDA content, and expression of cleaved-caspase-3, Bax, Fas, and FasL proteins increased, the LVEF, LVFS, and activity of SOD decreased (P < 0.05).

Conclusion Muscone may inhibit oxidative stress and cardiomyocyte apoptosis in DCM rats by inhibiting the Fas/FasL pathway.